Database driven website book

hello i have just tryed to install php mysql and apache to my laptop the same as my main comp everthing is working but when i try to go into mysql through command promt with this command mysql -u root -p then it takes me to the enter password then i get this error :

error 1045 (28000_: Access denied for user ‘root’ @’ localhost’ (useing password:yes)

i know 100% the password is correct i have unistalled all the programs and reinstalled them a few times now but i am still getting same error can some one help me thanks